Working on my hard playthrough atm so if it glitches, it probably was my fault but I'll update when I get done with the playthrough on what happens.

UPDATE: It popped after my second attempt at using cheats on hard. I was a moron and didn't save and quit after entering the cheats the first time so I made sure to do every step as it said in the opening post and after a crazy fight with Deadpool, the achievement unlocked. An amazing game but after 3 playthroughs, I finally have the 1000. Thank you OP for the post on the cheats. Saved so much time.